System and Method for Controlling Light Scattered from a Workpiece Surface in a Surface Inspection System

1. A system to analyze a surface of an object, comprising: a first radiation source; a radiation targeting assembly to scan a first radiation beam from the first radiation source across a portion of a first surface of the object, and to scan a second radiation beam across a portion of the first surface of the object, wherein the radiation targeting assembly comprises a wedged folded mirror in the optical path between the first radiation source and the first surface, such that a first portion of a radiation beam from the radiation source reflects from a front surface of the mirror and a second portion of the radiation beam from the radiation source reflects from a rear surface of the mirror; a scattered radiation collecting assembly to collect portions of a first scattered radiation beam scattered from the first surface, wherein the first scattered radiation beam results from a reflection of the first radiation beam, and to collect portions of a second scattered radiation beam scattered from the first surface, wherein the second scattered radiation beam results from a reflection of the second radiation beam; an illumination absorbing system to absorb at least a portion of the radiation generated by the first radiation source; a detector assembly coupled to the scattered radiation collecting assembly to generate a first signal from the first scattered radiation beam and a second signal from the second scattered radiation beam; a signal processing module to generate a data set from the first signal and the second signal as the first radiation beam and the second radiation beam scan a portion of the surface of the object; and a data processing module to use data in the data set to evaluate defects in the surface of the object; wherein a third portion of the radiation beam from the radiation source is internally reflected at the front surface of the reflected mirror and reflects from the rear surface of the mirror.

2. A system to analyze a surface of an object, comprising: a first radiation source; a radiation targeting assembly to scan a first radiation beam from the first radiation source across a portion of a first surface of the object, and to scan a second radiation beam across a portion of the first surface of the object, wherein the radiation targeting assembly comprises a wedged folded mirror in the optical path between the first radiation source and the first surface, such that a first portion of a radiation beam from the radiation source reflects from a front surface of the mirror and a second portion of the radiation beam from the radiation source reflects from a rear surface of the mirror; a scattered radiation collecting assembly to collect portions of a first scattered radiation beam scattered from the first surface, wherein the first scattered radiation beam results from a reflection of the first radiation beam, and to collect portions of a second scattered radiation beam scattered from the first surface, wherein the second scattered radiation beam results from a reflection of the second radiation beam; an illumination absorbing system to absorb at least a portion of the radiation generated by the first radiation source; a detector assembly coupled to the scattered radiation collecting assembly to generate a first signal from the first scattered radiation beam and a second signal from the second scattered radiation beam; a signal processing module to generate a data set from the first signal and the second signal as the first radiation beam and the second radiation beam scan a portion of the surface of the object; and a data processing module to use data in the data set to evaluate defects in the surface of the object; wherein the first portion of the radiation beam reflected from the mirror corresponds to the first radiation beam and the second portion of the radiation beam reflected from the mirror corresponds to the second radiation beam.

3. The system of claim 2 , wherein the intensity of the first radiation beam is less than ten percent of the intensity of the second radiation beam.

4. A system to analyze a surface of an object, comprising: a first radiation source; a radiation targeting assembly to scan a first radiation beam from the first radiation source across a portion of a first surface of the object, wherein the first radiation beam impinges the first surface at a first intensity and to scan a second radiation beam across a portion of the first surface of the object, wherein the second radiation beam impinges the first surface proximate the first beam and at a second intensity, greater than the first intensity; a scattered radiation collecting assembly to collect portions of a first scattered radiation beam scattered from the first surface, wherein the first scattered radiation beam results from a reflection of the first radiation beam, and to collect portions of a second scattered radiation beam scattered from the first surface, wherein the second scattered radiation beam results from a reflection of the second radiation beam; an illumination absorbing system to absorb at least a portion of the radiation generated by the first radiation source; a detector assembly coupled to the scattered radiation collecting assembly to generate a first signal from the first scattered radiation beam and a second signal from the second scattered radiation beam; a signal processing module to generate a data set from the first signal and the second signal as the first radiation beam and the second radiation beam scan a portion of the surface of the object; and a data processing module to use data in the data set to evaluate defects in the surface of the object, wherein the data processing module analyzes the data set to locate data points in the data set that were generated by the same defect in the surface and implements a dynamic range extension routine when a first data point in the data set exceeds a threshold.

5. The system of claim 4 , wherein the dynamic range extension routine: locates a second data point in the data set which was generated by the same defect as the first defect; and multiplies the value of the second data point by the intensity ratios of the first radiation beam and the second radiation beam.

6. A method to analyze a surface of an object, comprising: scanning a first radiation beam from the first radiation source across a portion of a first surface of the object, wherein the first radiation beam impinges the first surface at a first intensity, and scanning a second radiation beam across a portion of the first surface of the object, wherein the second radiation beam impinges the first surface proximate the first beam and at a second intensity, greater than the first intensity; collecting portions of a first scattered radiation beam scattered from the first surface, wherein the first scattered radiation beam results from a reflection of the first radiation beam, and portions of a second scattered radiation beam scattered from the first surface, wherein the second scattered radiation beam results from a reflection of the second radiation beam; removing at least a portion of the radiation generated by the first radiation source; generating a first signal from the first scattered radiation beam and a second signal from the second scattered radiation beam; generating a data set from the first signal and the second signal as the first radiation beam and the second radiation beam scan a portion of the surface of the object; using data in the data set to evaluate defects in the surface of the object; and positioning a wedged folded mirror in the optical path between the first radiation source and the first surface, such that a first portion of a radiation beam from the radiation source reflects from a front surface of the mirror and a second portion of the radiation beam from the radiation source reflects from a rear surface of the mirror; wherein a third portion of the radiation beam from the radiation source is internally reflected at the front surface of the reflected mirror and reflects from the rear surface of the mirror.

7. A method to analyze a surface of an object, comprising: scanning a first radiation beam from the first radiation source across a portion of a first surface of the object, wherein the first radiation beam impinges the first surface at a first intensity, and scanning a second radiation beam across a portion of the first surface of the object, wherein the second radiation beam impinges the first surface proximate the first beam and at a second intensity, greater than the first intensity; collecting portions of a first scattered radiation beam scattered from the first surface, wherein the first scattered radiation beam results from a reflection of the first radiation beam, and portions of a second scattered radiation beam scattered from the first surface, wherein the second scattered radiation beam results from a reflection of the second radiation beam; removing at least a portion of the radiation generated by the first radiation source; generating a first signal from the first scattered radiation beam and a second signal from the second scattered radiation beam; generating a data set from the first signal and the second signal as the first radiation beam and the second radiation beam scan a portion of the surface of the object; and using data in the data set to evaluate defects in the surface of the object; wherein the first portion of the radiation beam reflected from the mirror corresponds to the first radiation beam and the second portion of the radiation beam reflected from the mirror corresponds to the second radiation beam.

8. The method of claim 7 , wherein the intensity of the first radiation beam is less than ten percent of the intensity of the second radiation beam.

9. The method of claim 8 , wherein the first radiation beam and the second radiation beam are incident on the surface at location separated by less than 100 micrometers.

10. A method to analyze a surface of an object, comprising: scanning a first radiation beam from the first radiation source across a portion of a first surface of the object, wherein the first radiation beam impinges the first surface at a first intensity, and scanning a second radiation beam across a portion of the first surface of the object, wherein the second radiation beam impinges the first surface proximate the first beam and at a second intensity, greater than the first intensity; collecting portions of a first scattered radiation beam scattered from the first surface, wherein the first scattered radiation beam results from a reflection of the first radiation beam, and portions of a second scattered radiation beam scattered from the first surface, wherein the second scattered radiation beam results from a reflection of the second radiation beam; removing at least a portion of the radiation generated by the first radiation source; generating a first signal from the first scattered radiation beam and a second signal from the second scattered radiation beam; generating a data set from the first signal and the second signal as the first radiation beam and the second radiation beam scan a portion of the surface of the object; and using data in the data set to evaluate defects in the surface of the object; analyzing the data set to locate data points in the data set that were generated by the same defect in the surface; and implementing a dynamic range extension routine when a first data point in the data set exceeds a threshold.

11. The method of claim 10 , further comprising: locating a second data point in the data set which was generated by the same defect as the first defect; and multiplying the value of the second data point by the intensity ratios of the first radiation beam and the second radiation beam.

12. A system to analyze a surface of an object, comprising: a first radiation source; a radiation targeting assembly to scan a first radiation beam from the first radiation source across a portion of a first surface of the object, and to scan a second radiation beam across a portion of the first surface of the object; a scattered radiation collecting assembly to collect portions of a first scattered radiation beam scattered from the first surface, wherein the first scattered radiation beam results from a reflection of the first radiation beam, and to collect portions of a second scattered radiation beam scattered from the first surface, wherein the second scattered radiation beam results from a reflection of the second radiation beam; an illumination absorbing system to absorb at least a portion of the radiation generated by the first radiation source; a detector assembly coupled to the scattered radiation collecting assembly to generate a first signal from the first scattered radiation beam and a second signal from the second scattered radiation beam; and a power attenuation module, which: compares the first signal from the first scattered beam to a threshold; and attenuates the second radiation beam when signal from the first scattered beam exceeds the threshold.

13. The system of claim 12 , wherein the first radiation beam and the second radiation beam are incident on the surface at locations separated by less than 100 micrometers.

14. The system of claim 12 , further comprising an acousto-optical deflector assembly, and wherein the illumination absorbing system comprises at least one set of baffles in the acousto-optical deflector assembly to absorb residual stray radiation in the acousto-optical deflector.

15. The system of claim 12 , wherein the intensity of the first radiation beam is less than ten percent of the intensity of the second radiation beam.

16. The system of claim 12 , further comprising: a signal processing module to generate a data set from the first signal and the second signal as the first radiation beam and the second radiation beam scan a portion of the surface of the object; and a data processing module to use data in the data set to evaluate defects in the surface of the object, wherein the data processing module analyzes the data set to locate data points in the data set that were generated by the same defect in the surface.

17. The system of claim 12 , wherein the data processing module implements a dynamic range extension routine when a first data point in the data set exceeds a threshold.

18. The system of claim 12 , wherein the dynamic range extension routine: locates a second data point in the data set which was generated by the same defect as the first defect; and multiplies the value of the second data point by the intensity ratios of the first radiation beam and the second radiation beam.